Field of the Invention
The present invention relates to methods for repairing semiconductor processing equipment, and more particularly to repairing a substrate support pedestal.
Description of Related Art
The making of ceramics, and the joining of ceramic materials, may involve processes which require very high temperatures and very high contact pressures. For example, liquid phase sintering may be used to join ceramic materials together. The hot pressing/sintering of a large, complex ceramic piece requires a large physical space within a very specialized process oven. Heaters and electrostatic chucks used in semiconductor processing may be made of ceramic, and may be manufactured using a hot pressing process.
The use of ceramics in substrate support pedestals used in semiconductor processing has increased substantially over the last two decades. Substrate support pedestals (commonly called heaters, electrostatic chucks (or e-chucks or ESCs), vacuum chucks, vacuum pedestals, or just pedestals) are often active participants in the processing of semiconductor devices, and can provide numerous functions to assist in producing the desired process results. These functions can include, but are not limited to, heating, cooling, substrate clamping (either electrostatically or with vacuum), providing gases or vacuum to the substrate and its processing environment, and other functions. Ceramics have become the material of choice for many of these substrate support pedestals due to certain properties of ceramic materials, namely good electrical insulation, high operating temperatures, transparency to certain electric fields, excellent corrosion resistance, and good mechanical stability.
One drawback to the use of ceramics is the high cost associated with manufacturing these substrate support pedestals using ceramic materials. Ceramic substrate support pedestals typically cost tens of thousands of dollars each, and in some cases can exceed one hundred thousand dollars. A typical semiconductor manufacturing facility has thousands of substrate support pedestals. Due to the harsh operating environments, ceramic substrate support pedestals have a finite lifetime, typically lasting only 1 to 3 years. A large semiconductor fabrication factory can spend tens of millions of dollars per year on replacement ceramic substrate support pedestals.
One of the more common failings with a chuck or heater is that the top surface may become damaged, which may include pitting on the top surface, or warping. These types of failures may be seen as soon as three months into the life of the heater or chuck. Typical end-of-life for ceramic substrate support pedestals is caused by the top surface of the ceramic being worn, etched, cracked, or otherwise damaged, rendering the ceramic substrate support pedestal ineffective at producing the desired process results.
Presently, a damaged top surface of a substrate support pedestal may be refreshed by machining down to a new, smooth, defect free top surface. This may be done once, sometimes more, on many devices. The ceramic layer above an embedded heater, or above an RF antenna, is not too thick, because if the top layer is too thick then pedestal will not function at a high performance level. Thus, there is not much material available to allow for repeated machining of the top surface. Also, substrate support pedestals may be designed, or tuned, for use with a specific top layer thickness. A repair procedure which could result in a top layer of the same thickness as the original device may be preferred.
What is called for is a repair method which allows for the repair of substrate support pedestals such that the life of these very expensive items can be extended.